Positive automatic safety-brake



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No. 591,189. Patented Oct. 5,1897.

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A. 1E. C. LOTZ. POSITIVE AUTOMATIC SAFETY BRAKE.

No. 591,189. yPatented Oct. 5,1897;`

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ALFRED F. C. LOTZ, OF PITTSBURG, PENNSYLVANIA.

SPECIFICATION forming part of Letters Patent No. 591,189, dated October 5, 189'?.

Application filed December ll, 1896. Serial No. 615,361. (No model.) I

To u/ZZ whom, t may concern.-

Be it known that I, ALFRED F. C. LOTZ, a citizen of the United States, residing at Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Positive Automatic Safety-Brakes; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention has relation to safety appliances for elevators and other vehicles, and has for its object the provision of means and appliances whereby all danger of accident, by the dropping of an elevator or undue speed in other vehicles, such as inclined railways, is obviated, or at least reduced to a minimum.

T his invention consists in the provision of a safety attachment whereby an elevator or other vehicle will be stopped in its descent, in case of accident, by the movement of the vehicle itself, and this stoppage will not alone be absolute, but also so gradual as to obviate all danger of breaking or disarrangement of the safety mechanism.

This invention further consists in the construction, combination, and arrangement of parts more fully described hereinafter, and specically pointed out in the claims.

Referring to the accompanying drawings, Figure I is a side elevation, partly in section, of my safety appliance'in position on an elevator; Fig. 2, `a top view, and Fig. 3 an end view, of the same; and Figs. e, 5, and 6, views of modifications.

A and A are pieces of wrought-,iron composing the suspension-fork A, which receives the weight of the elevator, being joined together by bolts C and Cunder the top beam B of the elevator structure. j D is a hanger in which is fastened the main supporting-cable D',4 this hanger being fastened to the fork A by bolt D2. p,

E, E', E2, E2, E4, E5, E6, and E'7 are links connected to the fork A A' at E2,E9, El, and E11; also to the split collars F F at F2, F2, F4, and F5. Collars F F fit loosely around clutches G G', said clutches G G sliding on shaft H and prevented from turning on said shaft by means of keys I-I and H2. Shaft H has a right-handed screw II3 and aleft-handed screw HL1 at its opposite ends.- The threaded ends H3 and H4 of shaft H are screwed into the brake-shoes I I', which brake-shoes fit around the elevator I2 I3.

J J are guides for the brake-shoes I I' and are fastened to the elevatorframe B by suitable bolts b b. These guides serve to suspend the weight of the elevator on the brake-shoes I I when said shoes are l.pressed against the guides I2 I3.

K K are springs which serve to engage clutches G G with the clutch-jaws at each end of the hub of drum L when there is no tension on cable D.

The drum L is loose on the shaft H and is caused to rotate by the relative motion of the movable elevator and the stationary cable M.

\ LL2 are supports for the drum Land serve to hold said drum in a fixed position relative to the elevator-shaft in the usual way.

The cable M is wound around the drum L and is guided by means of the sheaves N N', said sheaves being held in proper position on the elevator by means of the supports N2 N3, said supports being permanently fastened to the frame work of the elevator.

The operation of the mechanism asv described is 'as follows: Vhen the cable DI is in a state of tension, the fork A A is raised rela tive to the framework of the elevator and the links E, E', E2, E3, E4, E5, E6, and E7 force the collars F F and the clutches G G in opposite directions, thereby compressing the springs K K. This releases the drum L and allows said drum to revolve freely on shaft H without 4causingthe remaining parts of the mechanism to `be put into operation. Thebrakeshoes I I' are normally at such a distance from theelevator-guides I2 I3 as to allow the elevator to run freely between said guides. The drum L is caused to rotate by means of Vthe relative motion of the elevator and the cable M, said cable being stationary. When the cable D is released from the state of tension, the springs K K'l are also released from a state of compression and will resume their original state, therebyv forcing the clutches G G to engage the clutch-jaws at each end of the drum L. As the elevator descends the drum L is caused to rotate, and this causes the clutches G G, which are now engaged with the drum L andy the shaft H, which is keyed to the clutches G G', to revolve. The rotation of the shaft H causes the brake-shoes I I to be forced against the guides I2 I3 by means of the right and left handed screws at the ends II3 H4 of the shaft II. The more the elevator descends the more will the mechanism revolve and the greater will be the pressure exerted by the brake-shoes I I against the guides I2 I3, and a point will at last be reached where the friction between the brake-shoes I Il and the guides 4I2 I3 will overcome or just balance the tendency of the elevator to descend. At this point the weight of the elevator will be suspended on the brakeshoes I I and the elevator will come to a stop. Any further tendency of the elevator to descend would only cause the brake-shoes I I to be pressed harder against the guides I2 I3.

To bring hack the mechanism to its original position, it is necessary to raise the elevator by some means other than by tension on cable D sufficiently to cause drum L to rotate far enough by reversed motion to bringl the brake-shoes I I to their original position, after which the tension may again be put on cable D@ said tension releasing the drum L from clutches G G', after which operation the Whole mechanism is entirely restored to its original position.

In the modifications shown in Figs. 4, 5, and 6 I have illustrated a device for operating the brake-shoes by means of a toggle-joint instead of the screw shown in Figs. l, 2, and 3. In this modified form of apparatus the shaft H carries a beveled gear-'wheel O, meshing with a wheel O, mounted on a shaft P, journaled at p. The shaft P is screw-threaded on its exterior and carries an interiorly-screwthreaded nut Q, provided with arms q g'. To the arms q q are hinged the inner ends r r of the toggle-levers R R', the outer ends of the arms R R' being pivotally attached at S S to the brake-shoes I I. It will be seen that the operation of this modified form of safety appliance is almost exactly the same as the form shown in Figs. l, 2, and S-that is, the shaft H is caused to revolve 'When tension is relaxed on the operating-cable of the vehicleand that this movement is transferred through the gearing O and O' t0 the shaft P, which in turn causes the nut Q to move downward and through the toggle-levers R R to press the i brake-slices against the guides I2 and I3.

While I have herein particularly shown and such, for instance, as inclined railways, where the brake-shoes can be pressed against either the rails or the slringers on which they are supported.

Vhat I claim, and des-ire to secure by Letters Patent, is-

1. The combination with a cable-operated vehicle of a safety appliance consisting of a pair of brake-shoes attached to a shaft, a sheave loosely mounted on said shaft, a clutch `for connecting said shaft and sheave and a cable adapted to rot-ate said sheave, and operate said brake-shoes, substantially as described.

2. The combination with a cable-operated vehicle of a safety appliance consisting of a revoluble shaft having right and left handed screws on its opposite ends, and brake-shoes screwed thereon, a loose sheave mounted on said shaft, a pair of clutches controlling the movement of said sheave, and operative devices controlled by the tension of the operating-cable of the elevator for controlling the movement of said clutches, substantially as described.

3. In a safety appliance for cable-operated vehicles the combination with a revoluble shaft, mounted on the vehicle and carrying brake-shoes on its opposite ends, of a loose sheave carried by said shaft, a spring-controlled clutch to connect said shaft and sheave, a cable to revolve the sheave and a series of links connecting the clutch and hanger of the elevator as and for the purpose i set forth.

4. In a safety appliance for cable-operated vehicles, the combination with a revoluble shaft mounted on said vehicle, aloose sheave surrounding said shaft and continually rotated by means of a cable, during the movement of the vehicle, and means for connecting said sheave and shaft, of a pair of brakeshoes operated by the revolution of said shaft and sheave, substantially as described.

In testimony whereof I aliix my signature in presence of two witnesses.

ALFRED F. C. LOTZ.

Witnesses:

J. BOYD DUrr, A. M. DUFF.

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